There are other registers in the PHY model which should be partially or
entirely read-only, but this solves the immediate issue.

Resolves: https://gitlab.com/qemu-project/qemu/-/issues/3297

Signed-off-by: Jim MacArthur <[email protected]>
---
See:

https://gitlab.com/qemu-project/qemu/-/issues/3297

https://lore.kernel.org/qemu-devel/CAJy5ezqTAMr=a3uafmuwlepk66adlru4q8amfmh4+4q2htd...@mail.gmail.com/

IEEE 802.3-2022 does not explicitly state that these registers
should be read-only, but suggests it in 22.2.4.3.1 which says this
information should be entirely manufacturer-supplied information.

The standard does mention several other registers in the set which
should be partially or entirely read-only, so further work may be
required.
---
 hw/net/xilinx_axienet.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/hw/net/xilinx_axienet.c b/hw/net/xilinx_axienet.c
index d85f8bb23f..970732b162 100644
--- a/hw/net/xilinx_axienet.c
+++ b/hw/net/xilinx_axienet.c
@@ -141,6 +141,10 @@ tdk_write(struct PHY *phy, unsigned int req, unsigned int 
data)
     regnum = req & 0x1f;
     DPHY(qemu_log("%s reg[%d] = %x\n", __func__, regnum, data));
     switch (regnum) {
+        case 2:
+        case 3:
+            /* Writes to PHY Identification registers are disallowed */
+            break;
         default:
             phy->regs[regnum] = data;
             break;

---
base-commit: 3fb456e9a0e9eef6a71d9b49bfff596a0f0046e9
change-id: 20260305-xilinx-phy-protection-c396a658d072

Best regards,
-- 
Jim MacArthur <[email protected]>


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